Question 12

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waecmaths question: 

Solve the equation ${{2}^{7}}={{8}^{5-x}}$

Option A: 

$\tfrac{5}{8}$

Option B: 

$\tfrac{8}{3}$

Option C: 

$\tfrac{3}{2}$

Option D: 

$\tfrac{15}{4}$

waecmaths solution: 

$\begin{align}  & {{2}^{7}}={{2}^{3(5-x)}} \\ & {{2}^{7}}={{2}^{15-3x}} \\ & \text{Equating the powers since the bases are equal} \\ & 7=15-3x \\ & 3x=8 \\ & x=\frac{8}{3} \\\end{align}$

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